Definition of bottom line noun from the Oxford Advanced Learner's Dictionary
bottom line
noun
[singular]
1the bottom linethe most important thing that you have to consider or accept; the essential point in a discussion, etcThe bottom line is that we have to make a decision today.2(business) the amount of money that is a profit or a loss after everything has been calculatedThe bottom line for 2008 was a pre-tax profit of £85 million.Sales last month failed to add to the company's bottom line.3the lowest price that somebody will acceptTwo thousand—and that's my bottom line!